Bitmap versus Vector Artwork in Flash CS5

In computer-based design, you need to be aware of two graphic types: bitmap and vector. The drawing environment in Flash natively creates vector graphics, but you can use both bitmap and vector graphics in a Flash movie.

Vector graphics refer to scalable artwork consisting of points, paths, and fills that the computer creates based on mathematical formulas. Though you may see a plain red rectangle, Flash sees an equation that creates the points, paths, and fill color necessary to create that rectangle.

Changing the rectangle’s size, position, or color is a matter of simply recalculating the formula and redrawing the shape. As a result, vector graphics maintain crisp quality even when scaled far beyond their original size. Flash (like its cousin Illustrator CS5) can natively create detailed vector illustrations and typography that you can easily scale or modify.

Bitmap graphics are created much like the picture on your TV set. If you’ve ever looked closely at a television screen, you’ve seen that the picture is created from lots of multicolored, tightly arranged dots. The same is true of bitmap graphics, which are created from many pixels of varying colors on your computer screen.

The detail of the image can vary based on how many pixels, or dots, are used per inch to create the image. This amount is referred to as dots per inch, or dpi. Because of the immense range of colors and detail that a bitmap image can re-create, it’s the format of choice for digital photographs and photo art.

Bitmap images are created with a certain amount of pixel data; rescaling the image means either eliminating that data or trying to create information where it didn’t exist before. For this reason, bitmaps are far more limited than vectors in terms of scalability and can lose quality quickly if scaled too far beyond their original size.

In the figure, both stars are zoomed at 400 percent. The bitmap image begins to pixelate as you zoom in, revealing the pixels that create it.